Short-Term Results of a Convertible Diaphyseal-fit Anatomic Shoulder Arthroplasty System

Background: The purpose of this analysis is to present a two-year follow-up of patient-reported outcomes, revision rate, and notable radiographic features of a convertible, diaphyseal-fit anatomic total shoulder arthroplasty system (ATSA).Methods: From June 2012 to June 2015, 100 shoulders were treated with ATSA using a convertible, diaphyseal-fit stem. Functional outcomes and radiographic findings were assessed preoperatively and at 6 months, 1 year, and 2 years postoperatively. Complications and reoperations were also determined.Results: Ninety-three shoulders were analyzed in this study. Patients were 47.3% male and had an average age of 67.3±8.1-years-old (range 44.7-89.1). Two-year clinical outcomes show a revision rate of 4.3%. Average preoperative ASES was 37.1±18.9 (6.7-86.7), SST (77.4%) was 3.1±2.4 yes responses (0-9), and SANE (88.2) was 25.4±21.5% (0-85.0%). At two years post-operative average (75% follow-up) ASES was 89.3±15.1 (37.0-100), SST was 10.0±2.5 yes responses (0-12), and SANE was 85.6%±17.0% (33.0-100%). Radiographic analysis at two years identified 2 shoulders (4%) with glenoid radiolucency (both Lazarus grade 1), 5 shoulders with at least one humeral radiolucent line (10%), and 9 shoulders (18%) with stress-shielding. There were 12 shoulders (24%) with distal pedestal formation. This finding was associated with the presence of radiolucent lines (P=0.002).Conclusion: This two-year analysis identified improvement in ASES, SST, and SANE scores and a low revision rate. presence presence of a distal pedestal was associated with increased rates of radiolucent lines. Further analysis with longer-term and more robust follow-up will improve our understanding of the risks and benefits of this shoulder system.